Roof Mining Drill Bit

ABSTRACT

In one aspect of the invention a rotary mine roof drilling apparatus has an arm attached to and intermediate a drill bit and a platform. The apparatus also has a thrusting mechanism adapted to push the drill bit into a mine roof. The drill bit has a bit body intermediate a shank and a working surface. The working surface has a cutting element with a carbide substrate bonded to a diamond working end with a pointed geometry; and the diamond working end has a 0.050-0.200 inch apex radius.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/7766,975 and was filed on Jun. 22, 2007. This application isalso a continuation-in-part of U.S. patent application Ser. No.11/774,227 which was filed on Jul. 6, 2007. U.S. patent application Ser.No. 11/774,227 is a continuation-in-part of U.S. patent application Ser.No. 11/773,271 which was filed on Jul. 3, 2007. U.S. patent applicationSer. No. 11/773,271 is a continuation-in-part of U.S. patent applicationSer. No. 11/766,903 filed on Jun. 22, 2007. U.S. patent application Ser.No. 11/766,903 is a continuation of U.S. patent application Ser. No.11/766,865 filed on Jun. 22, 2007. U.S. patent application Ser. No.11/766,865 is a continuation-in-part of U.S. patent application Ser. No.11/742,304 which was filed on Apr. 30, 2007. U.S. patent applicationSer. No. 11/742,304 is a continuation of U.S. patent application Ser.No. 11/742,261 which was filed on Apr. 30, 2007. U.S. patent applicationSer. No. 11/742,261 is a continuation-in-part of U.S. patent applicationSer. No. 11/464,008 which was filed on Aug. 11, 2006. U.S. patentapplication Ser. No. 11/464,008 is a continuation-in-part of U.S. patentapplication Ser. No. 11/463,998 which was filed on Aug. 11, 2006. U.S.patent application Ser. No. 11/463,998 is a continuation-in-part of U.S.patent application Ser. No. 11/463,990 which was filed on Aug. 11, 2006.U.S. patent application Ser. No. 11/463,990 is a continuation-in-part ofU.S. patent application Ser. No. 11/463,975 which was filed on Aug. 11,2006. U.S. patent application Ser. No. 11/463,975 is acontinuation-in-part of U.S. patent application Ser. No. 11/463,962which was filed on Aug. 11, 2006. U.S. patent application Ser. No.11/463,962 is a continuation-in-part of U.S. patent application Ser. No.11/463,953, which was also filed on Aug. 11, 2006. The presentapplication is also a continuation-in-part of U.S. patent applicationSer. No. 11/695,672 which was filed on Apr. 3, 2007. U.S. patentapplication Ser. No. 11/695,672 is a continuation-in-part of U.S. patentapplication Ser. No. 11/686,831 filed on Mar. 15, 2007. All of theseapplications are herein incorporated by reference for all that theycontain.

BACKGROUND OF THE INVENTION

This invention relates to drill bits, more specifically to improvementsin roof drill bits for drilling and boring in roof bolting operationsfor mining.

Such cutting elements are often subjected to intense forces, torques,vibration, high temperatures and temperature differentials duringoperation. As a result, stresses within the bit may begin to form. Dragbits for example may exhibit stresses aggravated by drilling anomaliesduring roof boring operations such as bit whirl or bounce oftenresulting in spalling, delamination or fracture of the super hardabrasive layer or the substrate thereby reducing or eliminating thecutting elements efficacy and decreasing overall drill bit wear life.Damage typically found in drag bits may be a result of shear failures,although non-shear modes of failure are not uncommon.

Roof bolt bits have been disclosed in the patent prior art. U.S. Pat.No. 5,535,839 by Brady et al., which is herein incorporated by referencefor all that it contains, discloses a roof bit that has two hardsurfaced inserts having domed working surfaces.

U.S. Pat. No. D529,937 by Brady et al., which is herein incorporated byreference for all that it contains, discloses the design for a heavyduty roof drill bit.

U.S. Pat. No. 5,848,657 by Flood et al, which is herein incorporated byreference for all that it contains, discloses domed polycrystallinediamond cutting element wherein a hemispherical diamond layer is bondedto a tungsten carbide substrate, commonly referred to as a tungstencarbide stud. Broadly, the inventive cutting element includes a metalcarbide stud having a proximal end adapted to be placed into a drill bitand a distal end portion. A layer of cutting polycrystalline abrasivematerial disposed over said distal end portion such that an annulus ofmetal carbide adjacent and above said drill bit is not covered by saidabrasive material layer.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the invention a rotary mine roof drilling apparatus hasan arm attached to and intermediate a drill bit and a platform. Theapparatus also has a thrusting mechanism adapted to push the drill bitinto a mine roof or wall. The drill bit has a bit body intermediate ashank and a working surface. The working surface has a cutting elementwith a carbide substrate bonded to a diamond working end with a pointedgeometry; and the diamond working end has a 0.050-0.200 inch apexradius.

In another aspect to the invention the working surface may have multiplecutting elements that aid in the drilling process. One cutting elementmay be substantially coaxial relative to the bit body and may aid instabilizing the bit as it rotates. The substantially coaxial cuttingelement may also be spring loaded so as to counter any blunt forces. Thesubstantially coaxial cutting element may also tilt relative to the bitbody creating an angle between the axis of the bit body and the axis ofthe cutting element. The cutting element may be placed on otherlocations of working surface and be placed off-centered relative to thebit body.

In another aspect to the invention the working surface may comprise acutting element that may be stationary as an outer cutting element mayrotate around it. Multiple cutting elements may be placed on the bitbody and may aid in the drilling process. The bit body is intermediatethe working surface and a shank that has at least one connectingcomponent that may attach to the arm. The arm attached to the shank maytelescope to bring the drill bit in and out of contact with a formation.

The pointed geometry of 0.050-0.200 inch apex radius at the end of thediamond working end may also have a thickness of at least 0.100 inch,and may have infiltrated diamond. The diamond may also have a metalcatalyst concentration of less than 5 percent by volume. The diamond maybe processed in a high temperature high pressure press, and cleaned in avacuum and sealed in a can by melting a sealant disk within the canprior to processing in the high temperature high pressure press. Thediamond may also be bonded to a carbide substrate at an interfacecomprising a flat normal to the axis of the cutting element. The diamondmay have a characteristic of being capable of withstanding greater than80 joules in a drop test with carbide targets, and have a central axisthat forms a 35-55 degree angle relative to a side of the diamond.

In some embodiments, the bits may be used for drilling and blasting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an orthogonal diagram of an embodiment of a roof miningmachine attached to a drill bit.

FIG. 2 is a perspective drawing of an embodiment of a roof mining drillbit.

FIG. 2 a is a top orthogonal diagram of a roof mining drill bit of theembodiment shown in FIG. 2.

FIG. 3 is a perspective diagram of another embodiment of a roof miningdrill bit.

FIG. 3 a is a top orthogonal diagram of a roof mining drill bit of theembodiment shown in FIG. 3.

FIG. 4 is a perspective diagram of another embodiment of a roof miningdrill bit.

FIG. 4 a is a top orthogonal diagram of a roof mining drill bit of theembodiment shown in FIG. 4.

FIG. 5 is a perspective diagram of another embodiment of a roof miningdrill bit.

FIG. 5 a is a cross-sectional of another embodiment of a roof miningdrill bit.

FIG. 6 is a perspective diagram of another embodiment of a roof miningdrill bit.

FIG. 7 is a cross-sectional diagram an embodiment of a diamond workingend.

FIG. 7 a is a cross-sectional diagram another embodiment of a diamondworking end.

FIG. 7 b is a cross-sectional diagram another embodiment of a diamondworking end.

FIG. 8 a is a cross-sectional diagram of another embodiment of a diamondworking end.

FIG. 8 b is a cross-sectional diagram of another embodiment of a diamondworking end.

FIG. 8 c is a cross-sectional diagram of another embodiment of a diamondworking end.

FIG. 8 d is a cross-sectional diagram of another embodiment of a diamondworking end.

FIG. 8 e is a cross-sectional diagram of another embodiment of a diamondworking end.

FIG. 8 f is a cross-sectional diagram of another embodiment of a diamondworking end.

FIG. 8 f is a cross-sectional diagram of another embodiment of a diamondworking end.

FIG. 8 h is a cross-sectional diagram of another embodiment of a diamondworking end.

FIG. 9 is a cross-sectional diagram of another embodiment of a roofmining drill bit.

FIG. 10 is a perspective diagram of an embodiment of a handheld rotarymine roof drilling apparatus.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENT

FIG. 1 is an orthogonal diagram of a roof mining machine 100 attached toa roof mining drill bit 101. An arm 102 may be intermediate the drillbit 101 and a platform 103. The arm 102 may be attached to a hydraulicsystem 104 that may allow the arm 102 to move. The arm 102 may also beable to telescope to bring the drill bit 101 in and out of contact withthe mine roof 105. A rotation device 106 may be attached to the arm 102and be in communication with the drill bit 101. The drill bit 101 mayrotate when the rotation device 106 is activated. The drill bit 101 maycomprise multiple cutting elements 107 adapted to engage the roof of themine 105 which may facilitate drilling.

FIG. 2 is a perspective diagram of a roof mining drill bit 101. Thedrill bit 101 may comprise a bit body 201 intermediate a working surface202 and a shank 203. The working surface 202 may comprise multiple outercutting elements 157 that comprise diamond working ends 204. Eachdiamond working end 204 may have a thickness of at least 0.100 to 0.500inch with a pointed geometry comprising an apex radius of 0.050-0.200inches. Generally, each diamond working end 204 is pointed in opposingdirections relative to one another, as shown in FIG. 2. The diamondworking end 204 may be bonded to a carbide substrate 205 at an interface206 comprising a flat The carbide substrate 205 may be brazed,press-fit, or a combination thereof to the working surface 202. Acutting element 107 may be placed substantially coaxial with the bitbody 201 and may aid in stabilizing the drill bit 101 as outer cuttingelements 157 rotate during the drilling process. As the drill bit 101rotates a new layer of formation may be dislodged by a passing cuttingelement 157. At least one canal 208 may be present in the drill bit 101to allow fluid to enter the bore hole and clear dislodged formations,cool the drill bit 101, soften the formation, or a combination thereof.

In some embodiments, the drill bit may be used to drill into a wall ofthe mine. The hole drilled may be filled with explosives which may thenbe ignited to open the hole.

FIG. 2 a is a top orthogonal diagram of a roof mining drill bit 101. Thebase 209 of each outer cutting element 157 and the substantially coaxialcutting element 107 may be parallel to one another. The cutting element107 that is substantially coaxial may also be slightly tilted inrelation to the axis of the bit body. Canals 208 for fluid may bepositioned on the sides of the drill bit 101.

FIG. 3 is a perspective diagram of a roof mining drill bit 101. Acutting element 107 may be off-centered relative to the bit body 201, asshown in FIG. 3. The shank 203 of the drill bit 101 may be adapted toattach to the arm 102 intermediate the drill bit 101 and a platform 103.The shank 203 may be made from steel, composites, carbide, matrix, or acombination thereof. Canals 208 for fluid to enter the formation may runalong the axis of the drill bit 101. The outer cutting elements 157 mayhave an axis 302 forming an angle 350 of 90-180 degrees with the axis303 of the bit body 201. The drill bit 101 may also comprise blades 301that may aid in the removal of formation as the drill bit 101 rotates.

FIG. 3 a is a top orthogonal diagram of a roof mining drill bit 101.FIG. 3 a shows a middle cutting element 107 off-centered and the outercutting elements 157 parallel relative to one another. Canals 208 forfluid may be positioned on the sides of the drill bit 101. Theoff-centered cutting element 107 may be placed on either side of theworking surface 202. The outer cutting elements 157 may also protrudeslightly outward from the bit body 201.

FIG. 4 is a perspective diagram of another embodiment of a roof miningdrill bit 101. Multiple outer cutting elements 157 may be placed on theshank 203 or on the bit body 201, as shown in FIG. 4. Placing multipleouter cutting elements 157 on the bit body 101 or shank 203 may help inthe drilling process and spread force loads among cutting elements 157improving the overall life of the bit. As the drill bit 101 rotates atleast one outer cutting element 157 may be in contact with the formationwhich may improve the drilling process.

FIG. 4 a is a top orthogonal diagram of a roof mining drill bit 101.Multiple outer cutting elements 157 may protrude laterally from thedrill bit 101. Multiple outer cutting elements 157 may also be on theworking surface 202 of the drill bit 101. The axis 402 of the outercutting element 157 on the bit body 201 relative to the diameter of theworking surface 202 may comprise a negative, neutral, or positive rakeangle 401.

FIG. 5 is a perspective diagram of a roof mining drill bit 101. In FIG.5 a cutting element 107 is intermediate two flat cutting elements 501.The flat inserts may be made of diamond and aid in the drilling process.In FIG. 5 a cutting element 107 is substantially coaxial and springloaded. The cutting element 107 may comprise a housing 503 thatcomprises fingers 504. The housing 503 may comprise a spring mechanism502. The spring mechanism 502 may be a coil spring, a compressionspring, a tension spring, Belleville spring, wave spring, elastomericmaterial, gas spring, or combinations thereof. The springs, such asBelleville springs, may be stacked in alternating directions resultingin greater deflection. The spring mechanism 502 may also be stacked inthe same direction creating a stiffer joint. Mixing and matchingdirections allow a specific spring constant and deflection capacity tobe designed. The cutting element 107 may comprise a diamond working end204 bonded to a carbide substrate 205. The carbide substrate 205 maycomprise flanges 505 that may ensure that the carbide substrate 205 willnot completely leave the housing 503.

FIG. 6 is a perspective diagram of another embodiment of a bi-centerroof mining drill bit 101. A cutting element 107 may be adapted toengage the formation first and stabilize the drill bit 101. An outercutting element 157 may rotate while degrading the formation.

Now referring to FIG. 7 through 7b the substrate 207 comprises a taperedsurface 761 starting from a cylindrical rim 704 of the substrate andending at an elevated, flatted, central region 701 formed in thesubstrate 207. The diamond working end 204 comprises a substantiallypointed geometry 700 with a sharp apex 702 comprising a radius of 0.050to 0.200 inches. It is believed that the apex 702 is adapted todistribute impact forces across the flatted region 701, which may helpprevent the diamond working end 204 from chipping or breaking. Thediamond working end 204 may comprise a thickness of 0.100 to 0.500inches from the apex to the flatted region 701 or non-planar interface,preferably from 0.125 to 0.275 inches. The diamond working end 204 andthe substrate 207 may comprise a total thickness of 0.200 to 0.700inches from the apex 702 to a base 703 of the substrate 207. The sharpapex 702 may allow the high impact resistant tool to more easily cleaverock or other formations.

The pointed geometry 700 of the diamond working end 204 may comprise aside which forms a 35 to 55 degree angle with a central axis of thecutting element, though the angle 755 may preferably be substantially 45degrees.

The pointed geometry 700 may also comprise a convex side or a concaveside. The tapered surface of the substrate may incorporate nodules 709at the interface between the diamond working end 204 and the substrate207, which may provide more surface area on the substrate 207 to providea stronger interface. The tapered surface 761 may also incorporategrooves, dimples, protrusions, reverse dimples, or combinations thereof.The tapered surface 761 may be convex, as in the current embodiment,though the tapered surface 761 may be concave.

Comparing FIGS. 7 and 7 b, the advantages of having a pointed apex 702as opposed to a blunt apex 705 may be seen. FIG. 7 is a representationof a pointed geometry 700 which was made by the inventors of the presentinvention which has a 0.094 inch radius apex and a 0.150 inch thicknessfrom the apex to the non-planar interface. FIG. 7 b is a representationof another geometry also made by the same inventors comprising a 0.160inch radius apex and 0.200 inch thickness from the apex to thenon-planar geometry. The super hard geometries were compared to eachother in a drop test performed at Novatek International, Inc. located inProvo, Utah. Using an Instron Dynatup 9250G drop test machine, the toolswere secured to a base of the machine such that only the super hardgeometry was exposed. The base of the machine was reinforced with astronger foundation to reduce spring and improve the accuracy of thetest. The target 710 comprising tungsten carbide 16% cobalt grademounted in steel backed by a 19 kilogram weight was raised to the neededheight required to generate the desired potential force, then droppednormally onto the super hard geometries. Each tool was tested at astarting 5 joules, if they passed they were retested with a new carbidetarget 710 and the force was increased by 10 joules per test until thetools failed. The pointed apex 702 of FIG. 7 surprisingly required about5 times more joules to break than the thicker geometry of FIG. 7 b.

It was shown that the sharper geometry of FIG. 7 penetrated deeper intothe tungsten carbide target 710, thereby allowing more surface area ofthe diamond working end 204 to absorb the energy from the falling targetby beneficially buttressing the penetrated portion of the super hardmaterial 506 effectively converting bending and shear loading of thediamond substrate into a more beneficial quasi-hydrostatic typecompressive forces drastically increasing the load carrying capabilitiesthe diamond working end 204. On the other hand since the embodiment ofFIG. 7 b is blunter the apex hardly penetrated into the tungsten carbidetarget 710 thereby providing little buttress support to the diamondsubstrate and caused the diamond working end 204 to fail inshear/bending at a much lower load with larger surface area using thesame grade of diamond and carbide. The average embodiment of FIG. 7broke at about 130 joules while the average geometry of FIG. 7 b brokeat about 24 joules. It is believed that since the load was distributedacross a greater surface area in the embodiment of FIG. 7 it was capableof withstanding a greater impact than that of the thicker embodiment ofFIG. 7 b.

Surprisingly, in the embodiment of FIG. 7, when the super hard geometry700 finally broke, the crack initiation point 750 was below the radius.This is believed to result from the tungsten carbide target 710pressurizing the flanks of the pointed geometry 700 (number not shown inthe fig.) in the penetrated portion, which results in the greaterhydrostatic stress loading in the pointed geometry 700. It is alsobelieved that since the radius was still intact after the break, thatthe pointed geometry 700 will still be able to withstand high amounts ofimpact, thereby prolonging the useful life of the pointed geometry 700even after chipping.

FIGS. 8 a through 8 g disclose various possible embodiments comprisingdifferent combinations of tapered surface 761 and pointed geometries700. FIG. 8 a illustrates the pointed geometry 700 with a concave side850 and a continuous convex substrate geometry 851 at the interface 761.FIG. 8 b comprises an embodiment of a thicker super hard material 852from the apex to the non-planar interface, while still maintaining thisradius of 0.075 to 0.125 inches at the apex. FIG. 8 c illustratesgrooves 863 formed in the substrate to increase the strength ofinterface. FIG. 8 d illustrates a slightly concave geometry at theinterface 853 with concave sides. FIG. 8 e discloses slightly convexsides 854 of the pointed geometry 700 while still maintaining the 0.075to 0.125 inch radius. FIG. 8 f discloses a flat sided pointed geometry855. FIG. 8 g discloses concave and convex portions 857, 856 of thesubstrate with a generally flatted central portion.

Now referring to FIG. 8 h, the diamond working end 204 (number not shownin the fig.) may comprise a convex surface comprising different generalangles at a lower portion 858, a middle portion 859, and an upperportion 860 with respect to the central axis of the tool. The lowerportion 858 of the side surface may be angled at substantially 25 to 33degrees from the central axis, the middle portion 859, which may make upa majority of the convex surface, may be angled at substantially 33 to40 degrees from the central axis, and the upper portion 860 of the sidesurface may be angled at about 40 to 50 degrees from the central axis.

FIG. 9 is a cross-sectional diagram a roof mining drill bit. FIG. 9shows cutting elements 107 that are electrically isolated. The cuttingelement 107 may be placed within a dielectric material 901. Thedielectric material 901 may be a ceramic, a rubber, a plastic, a metal,a gas or combinations thereof. Wires 902 may run through the dielectricmaterial 901 and be in communication with a power source. It is believedthat by electrically isolating the cutting elements 107 signals may besent into the formation to gather data. Electrically isolated cuttingelements may have the advantage of being capable of picking upelectrically signals from the formation, such as a laterolog resistivitysignal sent from another source. In some embodiments, current may bepassed through the electrically isolated cutting elements and may be thelaterolog resistivity source. In other embodiments, a transducer, suchas a magnetostrictive or piezoelectric transducer may be incommunication with the cutting elements which may be used to determineformation characteristics while drilling. Such measurments may helpminers identify potential minerals pay zones in the mines while drillingholes for the roof bolts.

FIG. 10 is a perspective diagram of a handheld rotary roof miningmachine 1000 attached to a drill bit 101. FIG. 10 shows a person 1002drilling a hole into the roof of a mine. The roof mining machine 1000may comprise a driving mechanism 1001 and a rotation device 106 thatrotates the drill bit 101. This may be advantageous in mines that arerelatively small and unable to accommodate larger machines.

Whereas the present invention has been described in particular relationto the drawings attached hereto, it should be understood that other andfurther modifications apart from those shown or suggested herein, may bemade within the scope and spirit of the present invention.

1. A rotary mine roof drilling apparatus, comprising; an arm attached toand intermediate a drill bit and a platform; a thrusting mechanismadapted to push the drill bit into a mine roof or wall; the drill bitcomprising a bit body intermediate a shank and a working surface; theworking surface comprising a cutting element with a carbide substratebonded to a diamond working end with a pointed geometry; and the diamondworking end comprising a 0.050-0.200 inch apex radius.
 2. The drillingapparatus of claim 1, wherein the working surface comprises multiplecutting elements.
 3. The drilling apparatus of claim 1, wherein thecutting element is substantially coaxial with the bit body.
 4. Thedrilling apparatus of claim 1, wherein the cutting element is springloaded.
 5. The drilling apparatus of claim 1, wherein the cuttingelement is bi-centered relative to the bit body.
 6. The drillingapparatus of claim 3, wherein the substantially coaxial cutting elementcomprises an axis adjacent the axis of the bit body.
 7. The drillingapparatus of claim 1, wherein working surface comprises one stationarydiamond and at least one cutting element that rotates around it.
 8. Thedrilling apparatus of claim 1, wherein the arm telescopes.
 9. Thedrilling apparatus of claim 1, wherein the pointed geometry comprises athickness of at least 0.100 inch.
 10. The drilling apparatus of claim 1,wherein the diamond working end is processed in a high temperature highpressure press.
 11. The drilling apparatus of claim 10, wherein thediamond working end is cleaned in a vacuum and sealed in a can bymelting a sealant disk within the can prior to processing in the hightemperature high pressure press.
 12. The drilling apparatus of claim 1,wherein the diamond working end comprises infiltrated diamond.
 13. Thedrilling apparatus of claim 1, wherein the diamond working end comprisesa metal catalyst concentration of less than 5 percent by volume.
 14. Thedrilling apparatus of claim 1, wherein the diamond working end is bondedto the carbide substrate at an interface comprising a flat normal to theaxis of the cutting element.
 15. The drilling apparatus of claim 1,wherein a surface of the diamond working end is electrically insulating.16. The drilling apparatus of claim 1, wherein the diamond working endcomprises an average diamond grain size of 1 to 100 microns.
 17. Thedrilling apparatus of claim 1, wherein the diamond working end comprisesa characteristic of being capable of withstanding greater than 80 joulesin a drop test with carbide targets.
 18. The drilling apparatus of claim1, wherein the diamond working end comprises a central axis thatcomprises a 35-55 degree angle relative to a side of the diamond. 19.The drilling apparatus of claim 1, wherein the shank comprises at leastone connecting component.
 20. The drilling apparatus of claim 1, whereinthe bit body comprises a cutting element.